them the place where the handle should have been, appeared of a
velvety blackness more intense than the rest of the background. The
writer was not able to make this observation. It coincides
interestingly with that of von Kries,[21] who reports as to the phases
of fading after-images, that between the disappearance of the primary
image and the appearance of the 'ghost,' a moment of the most intense
blackness intervenes. The experiments with the pendulum, however,
brought out no ghost.

[21] Von Kries, J., _Zeitschr. f. Psych, u. Physiol. d.
Sinnesorgane_, 1896, XII., S. 88.

We must now enquire why in about half the cases shape 3 is still seen,
whereas shape 5 occurs very rarely. Some of the subjects, among whom
is the writer, never saw 5 at all. We should expect that with the
intensity of _H_ sufficiently reduced 4 and 5 would appear with equal
frequency, whereas 3 would be seen no oftener than 2; shape 5
appearing when the eye did not, and 4 when it did, move at just the
rate of the pendulum. It is certain that when 4 is seen, the eye has
caught just the rate of the pendulum, and that for 3 or 5 it has moved
at some other rate. We have seen above (p. 27) that to move with the
pendulum the eye must already move decidedly more slowly than Dodge
and Cline find the eye generally to move. Nothing so reliable in
regard to the rate of voluntary eye-movements as these measurements of
Dodge and Cline had been published at the time when the experiments on
anæsthesia were carried on, and it is perhaps regrettable that in the
'empirical' approximation of the natural rate of the eye through 40°
the pendulum was set to move so slowly.

In any case it is highly probable that whenever the eye did not move